In 1936, Euler and Heisenberg [1]} proved that photons can interact with photons through the intermediate creation of electron-positron pairs, thus introducing nonlinear corrections to the Maxwell equations.
This interaction, being of second order in the fine structure constant \(\alpha \) , is difficult to observe in practical conditions. Nevertheless, there have been several works devoted to the small but not entirely negligible effects predicted by quantum electrodynamics. Some interesting effects are the induction of dichroism and birefringence in the quantum vacuum [2]}, [3]}, [4]}, [5]}, [6]}, the splitting of photons [7]}, [8]}, [9]}, [10]}, the bending of light by strong magnetic fields [11]}, [12]} and other processes related to the propagation of light [13]}, [14]}, [15]}, [16]}, [17]}, [18]}.
